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Answer

Crying on the Inside, Laughing on the Outside.

This is a common expression meant to convey that a person, although they might be sad, depressed, morose, anxiety-ridden internally, still tries to "put on a happy face" and present, to others and the outside world, a pleasant disposition.

The two "sides" of the rebus-body are identified as the "in" side and the "out" side. The Title: "Masque" is a fancy word for "mask": that "face" we put on to hide (sometimes) our true feelings from the world.Hide